Growth of dilute GaAsN alloys by low-energy nitrogen ion beam impinging during GaAs molecular beam epitaxy

Dilute GaAs_1-xN_x (x⩽4×10^-4 ) alloys were fabricated by impinging N ion beam (N⁺ and N₂⁺) during molecular beam epitaxy of GaAs. “x” was controlled by varying the GaAs growth rate in the range of 0.33-1.0 μm/h, while keeping the ion beam current density constant at 60-75 nA/cm. All samples were grown at the substrate temperature of 550°C. Secondary ion mass spectrometry (SIMS) showed that N atoms distributed uniformly in dilute GaAsN layers. In low-temperature photoluminescence spectra of the samples furnace-annealed at 750°C, peak-energy shift of band-to-carbon (C) acceptor emission, (e, C) towards lower energy region (red shift) was observed as x increases from zero. This is in evidence on the formation of GaAsN alloys since the red-shift was theoretically predicted owing to a large optical bowing parameter relevant to the GaAsN system